Abstract
46 feral rodents, including a common vole (Microtus arvalis), house mice (Mus musculus), muskrats (Ondatra zibetica), house rats (Rattus rattus) and brown rats (R. norvegicus) were examined for bacteria of the Haemophilus-Pasteurella-Actinobacillus group. Haemophilus spp. (only M. musculus examined) were not obtained. All animal species were found contaminated by P. pneumotropica and/or Actinobacillus spp. Almost all M. musculus (96%) and most Rattus spp. (76%) were contaminated by P. pneumotropica and/or Actinobacillus spp. These bacteria were obtained most frequently from the upper respiratory tract, to a lesser extent from the lung and rarely from caecal contents, It is concluded that feral rodents might constitute an important source of contamination of laboratory rodents by members of the HPA-group.